Fluorescence polarization

Fluorescence polarization is similar to fluorescence intensity, in that it is based on the emission of light by an excited fluorophore. However, samples are excited by polarized light which is selected by specific polarizing filters. Depending on the mobility of the fluorescent molecules in the wells, the emission light will either be polarized or not. Large molecules, such as proteins in solution, which rotate slowly due to their size, emit polarized light when excited by a polarized light. Smaller molecules, which rotate faster, emit depolarized light. Low levels of polarization indicate that the fluorescent molecules move freely in solution, whereas high levels of polarization mean that a larger molecule complex is present. Fluorescence polarization is generally applied to measure binding events.

Fluorescence polarization-based detection can be performed on all BMG LABTECH multi-mode plate readers, for example PHERAstar®FSX, CLARIOstar®, and POLARstar® Omega. A high-intensity xenon flashlamp provides high performance measurements, while assay-specific filters or Optic modules with specific polarization membranes select both a specific wavelength and polarized or depolarized light.